The Marathon Trilogy website is now offering free Mac and Win32 downloads of all three of the Marathon first person shooters from Bungie (Marathon, Marathon 2 and Marathon Infinity) along with editing tools and tutorials.
[i]Marathon is a series of first-person shooter games released for the Macintosh in the 1990's by Bungie, the company now best known for Halo. The series includes: Marathon, Marathon 2: Durandal and Marathon Infinity. The games are noteworthy for several reasons, among these that beyond simply being a run-and-shoot game they contain a coherent story, told in the form of dispatches from computer terminals you encounter while playing. And it's a pretty good story.